The use in silk screening machines for printing labels, artwork, descriptive material, etc. on containers or bottles is well known. Such machines are substantially automatic in operation beginning with the placement of a container on a bottle holding fixture or cradle. Upon such placement, the mouth of the container is engaged by an air chuck which inflates the container (if of a flexible material such as polystyrene, for example) to provide a solid surface for the screening, after which the fixture or cradle support mechanism is raised to a position just below the screen, and indexing means rotates each container to a precise starting position after which the indexing means is automatically disengaged. The silk screen squeegee is then automatically lowered and the silk screen moved laterally on its carriage, simultaneously rotating the container on its cradle fixture to screen the particular image on to the container.
Such silk screen printers as have heretofore been devised, however, are deficient in various respects, principally in that, because the mechanisms for automatically raising the container to screening height, and for effecting the screening stroke thereafter, operated independently of one another, and therefore uncoordinated except for being sequentially operative, resetting of these mechanisms was very time consuming. Thus, in effecting a "set-up" change-over it was necessary to stepwisely adjust, by trial and error, both the container raising mechanism and the silk screen stroke mechanism until proper coordination was empirically achieved. Since such procedures required the services of experienced technicians and could not ordinarily be accomplished by the machine operator, labor costs and loss of machine operating time involved in silk screening production, particularly of short runs on different diameter containers requiring frequent resetting of the screening height and stroke mechanisms, were substantial.
The present invention pertains to a semi-automatic silk screen printer device in which a "set-up" or change-over can be accomplished in a matter of minutes by a briefly trained mechanically apt operator. A simple measuring device is provided to determine the diameter of a cylindrical container in terms of an index reference numeral on a calibrated scale. The measuring device is attached to the stationary end of an air cylinder assembly in such a manner as to position the air cylinder relative to a container in said measuring device and an associated pivotal container cradle for sequentially carrying containers of a like diameter into proper abutting engagement with the underside of a silk screen for the printing sequence. To this end, the piston rod of the air cylinder is pivotally attached to the extended end of a pivoted cradle carriage assembly. An adjustable drive linkage driven by a second air cylinder, is provided with like index numeral graduations to provide for adjustment thereof to correlate horizontal reciprocating movement of the silk screen to the diameter of the containers being printed.
Accordingly, the principal object of the present invention is to provide calibrated scale measuring means for accurately determining the diameter of a container in terms of a reference or index number, including pivotal drive means connecting between the measuring means and a container supporting cradle assembly for sequentially moving the cradle from container load and unload position to a printing position, and back to a container load and unload position again.
Another object of the invention is to provide an adjustable linkage means in driving interconnection between a second air cylinder device and a silk screen carriage assembly fitted with a silk screen prepared in a conventional manner, to impart the desired printed material on each container while it is in the raised position.
Yet another object of this invention is to provide a like reference or index numeral scale on the adjustable linkage means enabling its accurate adjustment for imparting a horizontal reciprocating movement to the silk screen carriage assembly precisely correlated to the diameter of the container being printed.
A still further object of the invention is to provide third and fourth air cylinder drive means correlated to the movement of the silk screen carriage assembly for sequentially moving a squeegee and an ink flood bar, respectively, into and out of engagement with the upper surface of the silk screen.